1. Field of the Invention
The present invention is directed to a method for riveting two structural component parts, which are arranged so that their inner sides face one another and their outer sides face away from one another, in particular cover plate elements of a torsional vibration damper arrangement, at a distance from one another by at least one spacer rivet element.
2. Description of the Related Art
FIG. 1 is a longitudinal sectional view of a torsional vibration damper arrangement, designated in its entirety by 10, such as is used in the torque transmission path between a lockup clutch in a hydrodynamic torque converter and a driven shaft such as, e.g., the transmission input shaft, or generally in a wet multiple-disk clutch or the like. The torsional vibration damper arrangement 10 is constructed in two-tiered manner with two torsional vibration damper areas 12, 14 acting in series. An input area of the radially outer first torsional vibration damper area comprises a central disk element 16 connected by a plurality of rivet bolts 18 to an inner disk carrier 20 so as to be fixed with respect to rotation relative to it. An output area of this first torsional vibration damper area 12 comprises two cover plate elements 22, 24 arranged at a distance from one another in direction of an axis of rotation A. In their radially outer area, these cover plate elements 22, 24, like the center disk element 16, form circumferential supporting areas for the damper springs 26 of the first torsional vibration damper area 12.
The two cover plate elements 22, 24 form, in their radially inner area, the input area of the second torsional vibration damper area 14 and have in that location respective circumferential supporting areas for the damper springs 28 of the second torsional vibration damper area 14. Another center disk element 30 which is arranged on the radially inner side of the center disk element 16 provides circumferential supporting areas for the damper springs 28 and its radially outer area forms the output area of this second torsional vibration damper area 14. The center disk element 30 is fixedly connected on the radially inner side to a flange 34 of a hub 36 acting as driven element by a plurality of rivet bolts 32.
In order to obtain a defined, stable positioning of the two cover plate elements 22, 24 with the two center disk elements 16, 30 being received therebetween, the two cover plate elements are connected to one another in their radially inner area, i.e., also on the radially inner side of the damper springs 28 of the second torsional vibration damper area 14, by a plurality of rivet bolts 38 arranged successively in circumferential direction. In order to ensure a defined axial spacing, these rivet bolts 38 have a double-stepped longitudinal section with a spacing area 40, which is located between the two cover plate elements 22, 24, and end areas 42, 44 which project through the cover plate elements 22, 24. In order to produce a fixed connection, these end areas 42, 44, shown in undeformed state in FIG. 1, must be deformed by applying a corresponding riveting force to form rivet heads which then lie on the outer side of the two cover plate elements 22, 24.
Particularly under the influence of centrifugal force, the damper springs 28 of the radially inner second torsional vibration damper area 14, which are also supported at the cover plate elements 22, 24 on the radially outer side are forced outward and generate a force that loads the two cover plate elements 22, 24 in a direction away from one another. This can cause them to spread apart, which cancels the exact positioning of the two cover plate elements 22, 24 with respect to one another for purposes of a defined damping characteristic, also in the area of the first torsional vibration damper area 12.
To remedy this problem, the two cover plate elements 22, 24 are connected to one another in their area located between the damper springs 26 and 28, respectively, of the two torsional vibration damper areas 12, 14 by spacer rivet elements 46′. The only function of these spacer rivet elements 46′ is to prevent the two cover plate elements 22, 24 from spreading apart excessively. They do not serve to ensure a defined minimum axial distance and also do not serve to transmit torque between the two cover plate elements 22, 24. The respective rivet element end areas 52, 54 of the spacer rivet elements 46′ can be received in the associated rivet openings 48, 50 of the two cover plate elements 22, 24 while retaining a movement play so that it is possible in principle for the spacer rivet elements 46′ to tilt with respect to the two cover plate elements 22, 24. However, the rivet heads 56, 58 of the spacer rivet elements 46 engage behind the cover plate elements 22, 24 at their outer sides 60, 62 facing away from one another and prevent them from spreading apart excessively.
In order to provide an arrangement in the area of these spacer rivet elements which is as stable as possible, these spacer rivet elements are preferably formed in such a way that they have no step-like widened portion, for example, to allow the two cover plate elements 22, 24 to be supported on one another. Since this is not the function of these spacer rivet elements 46′, this would only run the unnecessary risk that stresses occur in the area of step-like transitions when the spacer rivet elements are loaded which could result in breakage.